But PostSecret founder Frank Warren says his phenomenally successful iPhone confessional couldn’t filter some of the uglier stuff out there.

“There was threatening content, there was bullying content and there were some gruesome images,” he says.

Warren, a Germantown resident who founded PostSecret 7 years ago, says the iPhone app took off fast with more than 2 million submissions in just four months. The concept was simple: Anyone with a secret he felt was worth sharing could take a photograph, write his secret on the photograph and submit it to the app to share it with users around the world.

“We had that content moderated 24 hours a day, 7 days a week,” Warren says. “We weren’t prepared for a small group of dedicated users that just seemed to want to bring it down.”

In the seven years since it was founded, the site has had half a billion hits. Warren continues to get postcard confessions — about 100 each day, he figures.

The cards have proven to be a draw in art galleries as well. A set of 300 PostSecret postcards was recently on display at the Museum of Modern Art in New York City. Warren also compiled three books that are themed collections based on the cards he’s received.

Warren says the secrets that are shared show the depth and range of human experience. Some people talk about abuse they suffered, habits about which they are ashamed or express feelings for others they found impossible to share in any other setting.

Warren says he’s sad he had to shut down the iPhone app, since it allowed for a sort of community of caring. He tells the story of one user who explained she’d be unable to deliver her daughter’s longed-for Christmas present — a ballerina music box — after it was sent to the wrong address. Another user tracked her down.

“And on Christmas day, that woman’s daughter was able to receive that ballerina music box because of this anonymous stranger who had purchased it for her,” Warren says.

Other simpler acts of kindness were performed via the PostSecret app. Warren says one user snapped a photo of a person dining alone and typed, “This person doesn’t realize it, but I’m about to pay for their meal.”